The disclosure relates to a light source unit and an optical engine that condense, with the use of a lens, light emitted from a phosphor in a transmissive phosphor wheel.
A discharged-based light source such as an ultrahigh pressure mercury lamp or a xenon lamp has been used for a projector. On the other hand, a configuration has been proposed in which light-emitting diodes or semiconductor lasers are used for a light source in consideration of superiority in decreased power consumption and a reduced environmental burden (for example, see Japanese Unexamined Patent Application Publication Nos. 2008-002518, 2012-088451, 2011-013313, 2011-065770, and 2004-341105).
In particular, high expectation is placed, as a high luminance projector that takes safety into consideration, on a hybrid projector in which a semiconductor laser device and a phosphor are used in combination.
For example, JP 2011-013313A discloses a projector including: the blue semiconductor laser device that generates blue light; a phosphor wheel that includes a phosphor region absorbing blue light and emitting green light, a phosphor region absorbing blue light and emitting red light, and a transmission region having a light diffusion effect; a motor that rotates the phosphor wheel in a circumferential direction; and a condenser lens group that is disposed in the vicinity of both front and back surfaces of the phosphor wheel.
In the projector disclosed in JP 2011-013313A, the blue light emitted from the blue semiconductor laser device is condensed and is applied to the phosphor wheel with the use of the condenser lens group disposed on the front side of the phosphor wheel, while rotating the phosphor wheel with the use of the motor. Further, the condenser lens group disposed on the back side of the phosphor wheel receives the red light and the green light that have been emitted from the respective phosphor regions in the phosphor wheel and the blue light that has passed through the transmission region, to thereby generate illumination light.
Also, JP 2004-341105A discloses a phosphor wheel that is coated with a phosphor absorbing blue-violet light and emitting blue light, a phosphor absorbing blue-violet light and emitting green light, and a phosphor absorbing blue-violet light and emitting red light.